In this chapter, we see V Nusjuro having the ability to use ice slashes. But imo, it wouldn't make sense for his DF to simply give him ice powers, because there already exists a mythical zoan that can do this: Yamato. There has to be something unique about V Nusjuro's powers that make him different from Yamato.
My theory? Whereas Yamato just has arbitrary ice powers, Nusjuro's goes much further with Nusjuro actually having powers of the dead similar to Brook.
Because Brook is undead, his soul has immense power and by channeling that power through his sword, he can produce a freezing slash. This is very likely exactly how Nusjuro's powers work.
Nusjuro is undead, just like Brook. He is a skeletal horse. What else would be keeping him alive if not his soul?
My guess is that as an awakened bakotsu, Nusjuro has powerful soul powers that probably surpass that of Brook or BM's. Just like Brook, Nusjuro's soul is what keeps him alive, not his body. And Nusjuro's soul is likely further enhanced by Ope Ope no mi immortality, just like all of the gorosei.
So yeah, in order to defect Nusjuro, Zoro will need to gain the ability to damage someone's soul. A perfect ability for the King of Hell imo.
